x86/vPMU: address violations of MISRA C Rule 20.7

MISRA C Rule 20.7 states: "Expressions resulting from the expansion
of macro parameters shall be enclosed in parentheses". Therefore, some
macro definitions should gain additional parentheses to ensure that all
current and future users will be safe with respect to expansions that
can possibly alter the semantics of the passed-in macro parameter.

No functional change.

Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/include/asm/vpmu.h

@@ -23,8 +23,8 @@
 #define MSR_TYPE_ARCH_CTRL          4
 
 /* Start of PMU register bank */
-#define vpmu_reg_pointer(ctxt, offset) ((void *)((uintptr_t)ctxt + \
-                                                 (uintptr_t)ctxt->offset))
+#define vpmu_reg_pointer(ctxt, offset) ((void *)((uintptr_t)(ctxt) + \
+                                                 (uintptr_t)(ctxt)->offset))
 
 /* Arch specific operations shared by all vpmus */
 struct arch_vpmu_ops {